<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        /* 选择器 */
        /* 文档流 排版流程 */
        
        * {
            margin: 0;
            padding: 0;
        }
        
        .specified-scope {
            width: 300px;
        }
        
        .specified-scope li {
            padding: 0 20px;
            /* height: 40px; */
            color: #fff;
            text-align: center;
            /* line-height: 40px; */
            background-color: black;
            list-style: none;
            position: relative;
            bottom: 10px;
            left: 10px;
            /* 副作用 盒子模型的一部分 改变了原有的盒子模型 */
            /* border-bottom: 1px solid green; */
        }
        /* css 伪类 状态 伪元素*/
        
        .specified-scope li:nth-child(odd) {
            /* background-color: red; */
        }
        
        .specified-scope li:nth-child(even) {
            /* background-color: #66f; */
        }
        
        .specified-scope li:hover {
            background-color: green;
            /* text-align: left; */
        }
        /* ::before 伪元素选择器 容器的内容开始之前 */
        
        .specified-scope li:before {
            content: '';
            /* border-bottom: 1px solid green; */
        }
        
        .specified-scope li::after {
            content: '';
            display: block;
            /* 定位会让元素离开文档流 */
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 1px;
            background-color: green;
        }
    </style>
</head>

<body>
    <div class="bruce">
        <ul class="specified-scope">
            <li>10001</li>
            <li>10002</li>
            <li>10003</li>
            <li>10004</li>
            <li>10005</li>
            <li>10006</li>
            <li>10007</li>
            <li>10008</li>
            <li>10009</li>
        </ul>
    </div>
</body>

</html>